/* eslint-disable no-constant-condition */
/* eslint-disable no-fallthrough */
// Use timsort because in most case elements are partially sorted
// https://jsfiddle.net/pissang/jr4x7mdm/8/
// https://github.com/mziccard/node-timsort
let DEFAULT_MIN_MERGE = 32;
let DEFAULT_MIN_GALLOPING = 7;

function minRunLength(n) {
  let r = 0;

  while (n >= DEFAULT_MIN_MERGE) {
    r |= n & 1;
    n >>= 1;
  }

  return n + r;
}

function makeAscendingRun(array, lo, hi, compare) {
  let runHi = lo + 1;

  if (runHi === hi) {
    return 1;
  }

  if (compare(array[runHi++], array[lo]) < 0) {
    while (runHi < hi && compare(array[runHi], array[runHi - 1]) < 0) {
      runHi++;
    }

    reverseRun(array, lo, runHi);
  } else {
    while (runHi < hi && compare(array[runHi], array[runHi - 1]) >= 0) {
      runHi++;
    }
  }

  return runHi - lo;
}

function reverseRun(array, lo, hi) {
  hi--;

  while (lo < hi) {
    let t = array[lo];
    array[lo++] = array[hi];
    array[hi--] = t;
  }
}

function binaryInsertionSort(array, lo, hi, start, compare) {
  if (start === lo) {
    start++;
  }

  for (; start < hi; start++) {
    let pivot = array[start];

    let left = lo;
    let right = start;
    let mid;

    while (left < right) {
      mid = (left + right) >>> 1;

      if (compare(pivot, array[mid]) < 0) {
        right = mid;
      } else {
        left = mid + 1;
      }
    }

    let n = start - left;

    switch (n) {
      case 3:
        array[left + 3] = array[left + 2]; //FIXME:fix this ugly code
      case 2:
        array[left + 2] = array[left + 1]; //FIXME:fix this ugly code
      case 1:
        array[left + 1] = array[left];
        break;
      default:
        while (n > 0) {
          array[left + n] = array[left + n - 1];
          n--;
        }
    }

    array[left] = pivot;
  }
}

function gallopLeft(value, array, start, length, hint, compare) {
  let lastOffset = 0;
  let maxOffset = 0;
  let offset = 1;

  if (compare(value, array[start + hint]) > 0) {
    maxOffset = length - hint;

    while (offset < maxOffset && compare(value, array[start + hint + offset]) > 0) {
      lastOffset = offset;
      offset = (offset << 1) + 1;

      if (offset <= 0) {
        offset = maxOffset;
      }
    }

    if (offset > maxOffset) {
      offset = maxOffset;
    }

    lastOffset += hint;
    offset += hint;
  } else {
    maxOffset = hint + 1;
    while (offset < maxOffset && compare(value, array[start + hint - offset]) <= 0) {
      lastOffset = offset;
      offset = (offset << 1) + 1;

      if (offset <= 0) {
        offset = maxOffset;
      }
    }
    if (offset > maxOffset) {
      offset = maxOffset;
    }

    let tmp = lastOffset;
    lastOffset = hint - offset;
    offset = hint - tmp;
  }

  lastOffset++;
  while (lastOffset < offset) {
    let m = lastOffset + ((offset - lastOffset) >>> 1);

    if (compare(value, array[start + m]) > 0) {
      lastOffset = m + 1;
    } else {
      offset = m;
    }
  }
  return offset;
}

function gallopRight(value, array, start, length, hint, compare) {
  let lastOffset = 0;
  let maxOffset = 0;
  let offset = 1;

  if (compare(value, array[start + hint]) < 0) {
    maxOffset = hint + 1;

    while (offset < maxOffset && compare(value, array[start + hint - offset]) < 0) {
      lastOffset = offset;
      offset = (offset << 1) + 1;

      if (offset <= 0) {
        offset = maxOffset;
      }
    }

    if (offset > maxOffset) {
      offset = maxOffset;
    }

    let tmp = lastOffset;
    lastOffset = hint - offset;
    offset = hint - tmp;
  } else {
    maxOffset = length - hint;

    while (offset < maxOffset && compare(value, array[start + hint + offset]) >= 0) {
      lastOffset = offset;
      offset = (offset << 1) + 1;

      if (offset <= 0) {
        offset = maxOffset;
      }
    }

    if (offset > maxOffset) {
      offset = maxOffset;
    }

    lastOffset += hint;
    offset += hint;
  }

  lastOffset++;

  while (lastOffset < offset) {
    let m = lastOffset + ((offset - lastOffset) >>> 1);

    if (compare(value, array[start + m]) < 0) {
      offset = m;
    } else {
      lastOffset = m + 1;
    }
  }

  return offset;
}

function TimSort(array, compare) {
  let minGallop = DEFAULT_MIN_GALLOPING;
  let runStart = [];
  let runLength = [];
  let stackSize = 0;
  let tmp = [];

  function pushRun(_runStart, _runLength) {
    runStart[stackSize] = _runStart;
    runLength[stackSize] = _runLength;
    stackSize += 1;
  }

  function mergeRuns() {
    while (stackSize > 1) {
      let n = stackSize - 2;

      if ((n >= 1 && runLength[n - 1] <= runLength[n] + runLength[n + 1]) || (n >= 2 && runLength[n - 2] <= runLength[n] + runLength[n - 1])) {
        if (runLength[n - 1] < runLength[n + 1]) {
          n--;
        }
      } else if (runLength[n] > runLength[n + 1]) {
        break;
      }
      mergeAt(n);
    }
  }

  function forceMergeRuns() {
    while (stackSize > 1) {
      let n = stackSize - 2;

      if (n > 0 && runLength[n - 1] < runLength[n + 1]) {
        n--;
      }

      mergeAt(n);
    }
  }

  function mergeAt(i) {
    let start1 = runStart[i];
    let length1 = runLength[i];
    let start2 = runStart[i + 1];
    let length2 = runLength[i + 1];

    runLength[i] = length1 + length2;

    if (i === stackSize - 3) {
      runStart[i + 1] = runStart[i + 2];
      runLength[i + 1] = runLength[i + 2];
    }

    stackSize--;

    let k = gallopRight(array[start2], array, start1, length1, 0, compare);
    start1 += k;
    length1 -= k;

    if (length1 === 0) {
      return;
    }

    length2 = gallopLeft(array[start1 + length1 - 1], array, start2, length2, length2 - 1, compare);

    if (length2 === 0) {
      return;
    }

    if (length1 <= length2) {
      mergeLow(start1, length1, start2, length2);
    } else {
      mergeHigh(start1, length1, start2, length2);
    }
  }

  function mergeLow(start1, length1, start2, length2) {
    let i = 0;

    for (i = 0; i < length1; i++) {
      tmp[i] = array[start1 + i];
    }

    let cursor1 = 0;
    let cursor2 = start2;
    let dest = start1;

    array[dest++] = array[cursor2++];

    if (--length2 === 0) {
      for (i = 0; i < length1; i++) {
        array[dest + i] = tmp[cursor1 + i];
      }
      return;
    }

    if (length1 === 1) {
      for (i = 0; i < length2; i++) {
        array[dest + i] = array[cursor2 + i];
      }
      array[dest + length2] = tmp[cursor1];
      return;
    }

    let _minGallop = minGallop;
    let count1;
    let count2;
    let exit;

    while (true) {
      count1 = 0;
      count2 = 0;
      exit = false;

      do {
        if (compare(array[cursor2], tmp[cursor1]) < 0) {
          array[dest++] = array[cursor2++];
          count2++;
          count1 = 0;

          if (--length2 === 0) {
            exit = true;
            break;
          }
        } else {
          array[dest++] = tmp[cursor1++];
          count1++;
          count2 = 0;
          if (--length1 === 1) {
            exit = true;
            break;
          }
        }
      } while ((count1 | count2) < _minGallop);

      if (exit) {
        break;
      }

      do {
        count1 = gallopRight(array[cursor2], tmp, cursor1, length1, 0, compare);

        if (count1 !== 0) {
          for (i = 0; i < count1; i++) {
            array[dest + i] = tmp[cursor1 + i];
          }

          dest += count1;
          cursor1 += count1;
          length1 -= count1;
          if (length1 <= 1) {
            exit = true;
            break;
          }
        }

        array[dest++] = array[cursor2++];

        if (--length2 === 0) {
          exit = true;
          break;
        }

        count2 = gallopLeft(tmp[cursor1], array, cursor2, length2, 0, compare);

        if (count2 !== 0) {
          for (i = 0; i < count2; i++) {
            array[dest + i] = array[cursor2 + i];
          }

          dest += count2;
          cursor2 += count2;
          length2 -= count2;

          if (length2 === 0) {
            exit = true;
            break;
          }
        }
        array[dest++] = tmp[cursor1++];

        if (--length1 === 1) {
          exit = true;
          break;
        }

        _minGallop--;
      } while (count1 >= DEFAULT_MIN_GALLOPING || count2 >= DEFAULT_MIN_GALLOPING);

      if (exit) {
        break;
      }

      if (_minGallop < 0) {
        _minGallop = 0;
      }

      _minGallop += 2;
    }

    minGallop = _minGallop;

    minGallop < 1 && (minGallop = 1);

    if (length1 === 1) {
      for (i = 0; i < length2; i++) {
        array[dest + i] = array[cursor2 + i];
      }
      array[dest + length2] = tmp[cursor1];
    } else if (length1 === 0) {
      throw new Error();
      // throw new Error('mergeLow preconditions were not respected');
    } else {
      for (i = 0; i < length1; i++) {
        array[dest + i] = tmp[cursor1 + i];
      }
    }
  }

  function mergeHigh(start1, length1, start2, length2) {
    let i = 0;

    for (i = 0; i < length2; i++) {
      tmp[i] = array[start2 + i];
    }

    let cursor1 = start1 + length1 - 1;
    let cursor2 = length2 - 1;
    let dest = start2 + length2 - 1;
    let customCursor = 0;
    let customDest = 0;

    array[dest--] = array[cursor1--];

    if (--length1 === 0) {
      customCursor = dest - (length2 - 1);

      for (i = 0; i < length2; i++) {
        array[customCursor + i] = tmp[i];
      }

      return;
    }

    if (length2 === 1) {
      dest -= length1;
      cursor1 -= length1;
      customDest = dest + 1;
      customCursor = cursor1 + 1;

      for (i = length1 - 1; i >= 0; i--) {
        array[customDest + i] = array[customCursor + i];
      }

      array[dest] = tmp[cursor2];
      return;
    }

    let _minGallop = minGallop;

    while (true) {
      let count1 = 0;
      let count2 = 0;
      let exit = false;

      do {
        if (compare(tmp[cursor2], array[cursor1]) < 0) {
          array[dest--] = array[cursor1--];
          count1++;
          count2 = 0;
          if (--length1 === 0) {
            exit = true;
            break;
          }
        } else {
          array[dest--] = tmp[cursor2--];
          count2++;
          count1 = 0;
          if (--length2 === 1) {
            exit = true;
            break;
          }
        }
      } while ((count1 | count2) < _minGallop);

      if (exit) {
        break;
      }

      do {
        count1 = length1 - gallopRight(tmp[cursor2], array, start1, length1, length1 - 1, compare);

        if (count1 !== 0) {
          dest -= count1;
          cursor1 -= count1;
          length1 -= count1;
          customDest = dest + 1;
          customCursor = cursor1 + 1;

          for (i = count1 - 1; i >= 0; i--) {
            array[customDest + i] = array[customCursor + i];
          }

          if (length1 === 0) {
            exit = true;
            break;
          }
        }

        array[dest--] = tmp[cursor2--];

        if (--length2 === 1) {
          exit = true;
          break;
        }

        count2 = length2 - gallopLeft(array[cursor1], tmp, 0, length2, length2 - 1, compare);

        if (count2 !== 0) {
          dest -= count2;
          cursor2 -= count2;
          length2 -= count2;
          customDest = dest + 1;
          customCursor = cursor2 + 1;

          for (i = 0; i < count2; i++) {
            array[customDest + i] = tmp[customCursor + i];
          }

          if (length2 <= 1) {
            exit = true;
            break;
          }
        }

        array[dest--] = array[cursor1--];

        if (--length1 === 0) {
          exit = true;
          break;
        }

        _minGallop--;
      } while (count1 >= DEFAULT_MIN_GALLOPING || count2 >= DEFAULT_MIN_GALLOPING);

      if (exit) {
        break;
      }

      if (_minGallop < 0) {
        _minGallop = 0;
      }

      _minGallop += 2;
    }

    minGallop = _minGallop;

    if (minGallop < 1) {
      minGallop = 1;
    }

    if (length2 === 1) {
      dest -= length1;
      cursor1 -= length1;
      customDest = dest + 1;
      customCursor = cursor1 + 1;

      for (i = length1 - 1; i >= 0; i--) {
        array[customDest + i] = array[customCursor + i];
      }

      array[dest] = tmp[cursor2];
    } else if (length2 === 0) {
      throw new Error();
      // throw new Error('mergeHigh preconditions were not respected');
    } else {
      customCursor = dest - (length2 - 1);
      for (i = 0; i < length2; i++) {
        array[customCursor + i] = tmp[i];
      }
    }
  }

  this.mergeRuns = mergeRuns;
  this.forceMergeRuns = forceMergeRuns;
  this.pushRun = pushRun;
}

export default function sort(array, compare, lo, hi) {
  if (!lo) {
    lo = 0;
  }
  if (!hi) {
    hi = array.length;
  }

  let remaining = hi - lo;

  if (remaining < 2) {
    return;
  }

  let runLength = 0;

  if (remaining < DEFAULT_MIN_MERGE) {
    runLength = makeAscendingRun(array, lo, hi, compare);
    binaryInsertionSort(array, lo, hi, lo + runLength, compare);
    return;
  }

  let ts = new TimSort(array, compare);

  let minRun = minRunLength(remaining);

  do {
    runLength = makeAscendingRun(array, lo, hi, compare);
    if (runLength < minRun) {
      let force = remaining;
      if (force > minRun) {
        force = minRun;
      }

      binaryInsertionSort(array, lo, lo + force, lo + runLength, compare);
      runLength = force;
    }

    ts.pushRun(lo, runLength);
    ts.mergeRuns();

    remaining -= runLength;
    lo += runLength;
  } while (remaining !== 0);

  ts.forceMergeRuns();
}
